CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In-Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2018	$ 97,883	$ 21	$ 337,627	$ (239,756)	$ (9)
Beginning balance, shares at Dec. 31, 2018		21,492
Issuance of common stock	1,863	$ 1	1,862
Issuance of common stock, shares		135
Stock-based compensation	3,477		3,477
Net loss	(7,068)			(7,068)
Other comprehensive income (loss)	16				16
Ending balance at Mar. 31, 2019	96,171	$ 22	342,966	(246,824)	7
Ending balance, shares at Mar. 31, 2019		21,627
Beginning balance at Dec. 31, 2018	97,883	$ 21	337,627	(239,756)	(9)
Beginning balance, shares at Dec. 31, 2018		21,492
Net loss	(15,307)
Other comprehensive income (loss)	45
Ending balance at Sep. 30, 2019	102,536	$ 22	357,541	(255,063)	36
Ending balance, shares at Sep. 30, 2019		22,128
Beginning balance at Mar. 31, 2019	96,171	$ 22	342,966	(246,824)	7
Beginning balance, shares at Mar. 31, 2019		21,627
Issuance of common stock	1,049		1,049
Issuance of common stock, shares		134
Stock-based compensation	3,543		3,543
Net loss	(4,158)			(4,158)
Other comprehensive income (loss)	27				27
Ending balance at Jun. 30, 2019	96,632	$ 22	347,558	(250,982)	34
Ending balance, shares at Jun. 30, 2019		21,761
Issuance of common stock	5,190		5,190
Issuance of common stock, shares		367
Stock-based compensation	4,793		4,793
Net loss	(4,081)			(4,081)
Other comprehensive income (loss)	2				2
Ending balance at Sep. 30, 2019	102,536	$ 22	357,541	(255,063)	36
Ending balance, shares at Sep. 30, 2019		22,128
Beginning balance at Dec. 31, 2019	125,239	$ 22	387,926	(262,743)	34
Beginning balance, shares at Dec. 31, 2019		22,217
Issuance of common stock	2,014	$ 1	2,013
Issuance of common stock, shares		460
Stock-based compensation	5,221		5,221
Net loss	(4,326)			(4,326)
Other comprehensive income (loss)	71				71
Ending balance at Mar. 31, 2020	128,219	$ 23	395,160	(267,069)	105
Ending balance, shares at Mar. 31, 2020		22,677
Beginning balance at Dec. 31, 2019	125,239	$ 22	387,926	(262,743)	34
Beginning balance, shares at Dec. 31, 2019		22,217
Net loss	(36,206)
Other comprehensive income (loss)	(22)
Ending balance at Sep. 30, 2020	109,428	$ 23	408,342	(298,949)	12
Ending balance, shares at Sep. 30, 2020		23,001
Beginning balance at Mar. 31, 2020	128,219	$ 23	395,160	(267,069)	105
Beginning balance, shares at Mar. 31, 2020		22,677
Issuance of common stock	1,015		1,015
Issuance of common stock, shares		109
Stock-based compensation	4,597		4,597
Net loss	(17,534)			(17,534)
Other comprehensive income (loss)	(47)				(47)
Ending balance at Jun. 30, 2020	116,250	$ 23	400,772	(284,603)	58
Ending balance, shares at Jun. 30, 2020		22,786
Issuance of common stock	1,887		1,887
Issuance of common stock, shares		215
Stock-based compensation	5,683		5,683
Net loss	(14,346)			(14,346)
Other comprehensive income (loss)	(46)				(46)
Ending balance at Sep. 30, 2020	$ 109,428	$ 23	$ 408,342	$ (298,949)	$ 12
Ending balance, shares at Sep. 30, 2020		23,001